A tool called Task Manager in the Windows XP operating system available from Microsoft Corporation, has a tab 100 for performance metrics, wherein four graphical displays of system performance are shown as illustrated in FIG. 1A. Two graphical displays 101 and 102 are for a current point in time, and respectively show the current CPU Usage, and PF Usage. Two additional graphical displays 103 and 104 in tab 100 show the CPU Usage History, and Page File Usage History. Display 101 for CPU Usage shows the amount of current processor usage, expressed as a percentage of total capacity. Display 103 for CPU Usage History shows the percentage of CPU capacity used over time. Display 102 for PF Usage shows the amount of virtual memory that has been “committed” or used. Display 104 for Page File Usage History shows usage of virtual memory over time.
Displays 103 and 104 appear to be showing actual metric values on the Y-axis, as measured. When fixed thresholds are used to generate alerts, they can be projected onto the time series graphs in displays 103 and 104 as horizontal lines intersecting Y-axis at threshold values, perhaps with some color distinguishing the type of threshold (e.g. WARNING=yellow and RED=critical). Note that the two graphical displays 103 and 104 in FIG. 1A are displayed in a common single screen 100, and note further that their respective X-axes move in synchronization with one another. Such synchronous movement of X-axes permits a human operator to visually identify a correlation, if present, between peaks and/or valleys in the two metrics in graphical displays 103 and 104.
The inventors note the following shortcomings with the display of the actual time series of raw data, of the type shown in FIG. 1A. Although graphical display 103 has a fixed range of 0-100%, graphical displays 103 and 104 in FIG. 1A have Y-axis dimensions that are specific to the metric displayed in each chart. For example the units for chart 103 are percentages while the units in chart 104 are MB of memory. This precludes making useful conclusions from similar chart features that may happen to occur across the two metrics series.
FIG. 1B illustrates a graphical display 110 presented by a feature called “Performance Monitor” included in a tool called “Microsoft Management Console” in the Windows XP operating system. In display 110, three lines 111, 112 and 113 (in three different colors) respectively show the following metrics (1) pages/sec, (2) % processor Time, and (3) Avg. Disk Queue Length. The three metrics in FIG. 1B are all shown with a common Y axis which has the range 0-100. A line 114 separates the more recent measurements (on the left side) from the earlier measurements (on the right side), and line 114 moves to the right as the graphs are re-drawn.
The inventors note that the display of FIG. 1B (as well as FIG. 1A) has a problem, namely that such a display becomes easily dominated by one or more measurements (called “outliers”) of a metric, if their values (on the Y axis) are significantly larger than the rest of the measurements of the metric. While such outliers may be of some interest, the visual impact of their display becomes disproportionate, especially if the metric (e.g. page file usage or average disk queue length) has an unknown maximum.
FIG. 1C illustrates a prior art display, in an ellipse 120, of a metric that is naturally represented as a percentage (such as buffer cache hit ratio), with the range of values 0-100 shown along horizontal axis 123, and a current value for the metric shown as a vertical line 122. Note that also displayed in FIG. 1C is an “X” that is labeled 124 which represents a mean of prior measurements, and a circle 121 centered at the mean 124 with a radius of one standard deviation distance.